Regional speech patterns or just laziness?

[KitSileya]

45. This is English evolving in the way spoken languages always do.

The changes in spoken languages are mainly directed by two forces, and these two forces are in conflict with each other.

The first is to economize on the energy used to say something. As you speak, you try to say as much as possible while using as little energy as possible. That is why sounds change and words contract together, depending on the environment in which it is said (that is, the words/sounds coming right before and after.) It is why we say I'm and don't, instead of I am and do not, and why it is iMpossible, yet iNcalculable. The M phoneme is a nasal pronounced using the lips, and the P phoneme is a plosive pronounced in the same place in the mouth, so instead of using the alveolar nasal N in front of P and B, we use M (even if the spelling should indicate otherwise, we assimilate sounds based on their environs, and would have to make conscious effort to say iNpossible, for example.)

The second is to make yourself understood. You want people to understand what you are saying, so you use energy to make your speech distinct enough that the listener can understand what you are trying to convey.

In groups, we have tons of shorthand, though. The previously mentioned don't, I'm and others are contracted forms akin to your examples. If most people agree what they stand for, it is very natural to start using them.

Believe me, you (and I!) may bellyache and moan about the evolution of English, and how everything is going downhill, but let's face it, if English didn't change, it would be because it was dead. What I see quite a lot of, though, is complaining because they feel that the changes are coming from the wrong people (read, the lower classes). One thing that drives me up the tree is using the gerund instead of the continuous form - He was sat under the tree, rather than he was sitting under the tree. But this is becoming more and more common in British English, and before my teaching career is over, I am pretty sure that I will have to accept my students using that form rather than what I learnt was correct.